There are several significant changes in this year's secondary school league tables in England.

The new benchmark - the "gold standard", as the government describes it - is the proportion of pupils attaining the Level 2 threshold (five or more GCSEs at A* to C or equivalent), including English and maths GCSEs.

This standard was reached by 45.8% of pupils, the tables confirm (the provisional figures were published in October): 43.8% of pupils in state schools and 71% of those in the independent sector - of which more in a moment.

On the old measure, of five good GCSEs in any subjects, the national average was 59.2%.

But the annual tables are about the performance of individual schools rather than the national averages for pupils.

English and maths

On that new English-and-maths measure, 114 schools had 100% attainment, including 34 state schools.

The best - using the average point score as a tie-break - was Chelmsford County High School for Girls, a foundation girls' grammar, where the average points score was 738.1.

Acting head Glynis Howland said a single sex education could be vital.

"When you're in a mixed class, you know what the boys are like - they nudge the girls aside, get on the keyboard and the girls don't get a look in."

The worst school was ... well, here we have to take into account a complication which the Independent Schools Council has denounced as making the tables "distorted and largely meaningless".

Yarm School students find the government's maths puzzling

Many highly regarded independent schools choose to enter their pupils for International GCSEs (IGCSEs) in English and/or maths.

But those are not approved for use in state schools - and they are not taken into account in the government's performance tables.

When the benchmark was any five good GCSEs this did not matter - because those schools were usually entering pupils for rather more than that.

But now that the benchmark requires English and maths GCSEs, they are left exposed.

'Indian head massage'

It is as if they are being assessed on how many red blazers they have when they all wear blue or green ones.

The head of Brighton College, Richard Cairns, said his current lower sixth were shown as having achieved only 59% in their GCSEs last year - but when their IGCSE results were included the figure was 98%.

He said IGCSE mathematics "is widely held to be a more challenging exam and much better preparation for A-level mathematics".

"But at this time every year schools that have made the transition pay the price as league tables are issued which give no recognition of IGCSE at all, while awarding points aplenty for floristry, hairdressing, Indian head massage and cake decorating."

There's no doubt that the introduction of this new measure has proved difficult for this school

Neil McAreeSchool with worst GCSE results

Among maintained schools, the worst was Temple School, a secondary modern in Strood, Rochester, Kent, where 2% of the 127 pupils got Level 2 with English and maths.

The head of the boys' school, Neil McAree, said he was disappointed but teachers had taken steps to improve standards for this year.

"There's no doubt that the introduction of this new measure has proved difficult for this school.

"We are a school that is operating in an area with grammar schools that are taking the top 25% of pupils.

"A lot of boys just missed out by getting a grade D in English or maths."

The effect of the change is that the tables in some areas are transformed, with schools that apparently used to do well shown to be not so strong on the basics.

Ministers make no apology for having "raised the bar" in this way.

Schools Minister Jim Knight said mastering the basics of English and maths at a good level should be "the expectation for every child in every school".

Where it was not happening he expected local authorities to intervene and the usual answer would be to set up an academy.

Alternative measure

This might be seen as somewhat tough when, throughout 2005, the government misled schools as to what the benchmark would be - only finally settling on actual English and maths GCSEs at the end of that year.

Indeed its tables include separate indicators for the proportion of pupils mastering other "functional skills" qualifications in literacy and numeracy - which it had led schools to believe might be acceptable.

And ironically, the government's own investigation into 14 to 19 learning, by former Ofsted chief Sir Mike Tomlinson, concluded that having even a top grade GCSE in English and maths was no proof at all that a youngster had grasped the basics - as employers never cease to point out.

For this reason it is changing the GCSEs - but not until the turn of the decade.

Academies

Two dozen academies - independent state schools which have outside backers - have been open long enough to feature in this year's tables.

Their fortunes are mixed.

At the top, Haberdashers' Aske's Hatcham College in New Cross, London, had 91% of its 204 Key Stage 4 pupils getting level 2 with English and maths.

At the other end of the table, the Marlowe Academy in Ramsgate, Kent, managed 5%.

In between, 14 had less than a quarter of their pupils getting the English and maths benchmark.

The government insists they are doing a good job.

It is true that most are doing well by their pupils on the new progress measure, known as CVA - the second big change in this year's league tables.

Contextual value added

Value added measures compare each pupil's GCSE results with those of all pupils nationally who had similar attainment when they left primary school.

This has now been enhanced by factoring in a number of things which the government says can affect children's attainment, but over which schools have no control.

The new contextual value added (CVA) measure is supposed to be a better reflection of the effect the school has.

Not all our pupils are always going to be able to achieve C grades at GCSE

The top school in the country on this basis is a multi-faith United Learning Trust academy in Liverpool, St Francis of Assisi, with a score of 1078.7 (the measure is based around 1000).

On the other key benchmark, the English and maths GCSEs, it scored 17%.

Assistant principal John Drane said CVA was a fairer way to judge schools in deprived areas.

"We are just really pleased that it does justify the work we do," he said.

"Not all our pupils are always going to be able to achieve C grades at GCSE. But this shows that they still make the expected progress - or better than the expected progress - given their ability and where they came to us from."

Selection

At the other end of the table is Eastbourne Comprehensive in Darlington, Co. Durham, with a CVA measure of 919.2 (and an English-and-maths score of 15%).

The 164 grammar schools generally fare worse under this system than the old one. The highest ranked is 288th, whereas last year the highest (Tiffin Girls') was 10th.

About 100 (61%) have CVA scores that show their pupils did make above-average progress, significantly so statistically in 28 of them (17%).

But in the other 64 (39%), pupils made less progress than predicted, and in seven of them (4%) significantly less.

So would they have been better off in the local comprehensive?

In 1,438 of the 2,720 comprehensives (53%) their pupils made better-than-predicted progress, significantly so statistically in 795 of them (29%).

In the other 1,282 (47%), pupils made less progress than predicted, and in 715 of them (26%) significantly less.

Now let us look at the 180 secondary moderns. In 98 of them (54%) pupils made better progress than predicted - significantly so in 60 (33%).

Progress was less than it should have been in 82 (46%), significantly so in 44 (24%).

In the top 25% of schools for CVA (scores of 1011.14 and above), 7% are secondary moderns - which make up 5.8% in the general school population. So they are over-represented.

Grammars account for 3.5% compared with 5.4% generally (so are under-represented). And comprehensives are 89.5% compared with 88.4% of all schools (just slightly more than they should be).

Officials acknowledge it is more difficult for schools that take in high-attaining children to "add value".

A/AS-levels

Results this year are not directly comparable with previous years' because there is a new points system.

In the past few years, the tables have used the Ucas "tariff" but that does not cover all the "equivalent" vocational qualifications now reflected in the tables.

So the QCA is using its own points system.

Top nationally this year is Colchester Royal Grammar School, with 1257.6 average level 3 points per student.

Local authorities

As usual Isles of Scilly comes top, with 77.8% getting the Level 2 including English and maths, and a CVA score of 1023.3.

Among the 148 mainland authorities (City of London doesn't have any maintained secondary schools):